One of the ten commandments that God gave Moses was not to commit adultery. Doing so would be a sin against God. The Jewish law was to stone to death those caught in adultery.
One day religionists brought a woman that was caught in adultery to Jesus. They wanted to see if Jesus would uphold the Jewish law and condemn this woman to death.
This was Jesus' response, "If any one of you is without sin, let him be the first to throw a stone at her [the woman caught in adultery]." — John 8:7
It is easy for us to identify the sins of others and focus on those sins instead of the fact that we all are sinners and each of us falls short. Please know that God wants to deliver us from the sin of being critical and judgmental.
